Wang Weijun said he felt a kick in his stomach each time he saw his daughter sitting alone in the last row of her middle school classroom. But he said he always swallowed his complaints.

Wang's daughter, Kaijia, is 16 and has lived with HIV since 1999.

Her teachers have her sit alone, fearing that the girl could spread the virus to other children, even though scientific research shows that HIV cannot be transmitted through casual contact.

Kaijia contracted the virus from her mother, who was infected through a blood transfusion during childbirth. The mother died two years after Kaijia was born.

"If I'd complained, I would have put my daughter at greater risk to have her HIV-status exposed," Wang, from Hebei province, says. "At least my daughter can stay at school because very few of her classmates have known her status and her teachers have treated her well on [the] surface."

Wang's situation illustrates the plight faced by many mainland families with relatives infected with HIV/Aids, where the numbers with the illness are growing.

Today marks World Aids Day and with the theme Getting to Zero, the vulnerability of adolescents and young people with HIV/Aids infections has gained prominence. Children living with the virus or those who have lost one or both parents to it often face social stigmas and financial constraints.

The Ministry of Civil Affairs said in 2009 that it would subsidise all children affected by HIV/Aids.

Since 2010, children with Aids or HIV as well as those who have lost a parent to the virus are entitled to 600 yuan (HK$800) a month. Most families haven't received any money, advocates say.

Wang, who is now an Aids activist, says he quit his job after his wife's death to care for his daughter and older son. The family receives 780 yuan a month in government subsistence allowances, which have nothing to do with the HIV. Wang's daughter should be given another 300 yuan a month under another set of government policies established in 2010, but the family hasn't received the money, Wang says.

When he has time, Wang takes menial jobs such as working as a part-time mechanic to make ends meet.

For some other families, government payments have been suddenly halted.

Xu Meizi of Dali in Yunnan province said she contracted the virus from her former boyfriend, who was a drug addict, and passed it on to her son, who is now seven years old. Xu said it was not until April this year that her son received his first government allowance.

He received payments for six months and then they stopped for "lack of matching funds", she said. A Yunnan Aids advocacy group supported her claim.

Wan Yanhai, founder of the advocacy group People With HIV/Aids Aizhixing, says the governments have been dishonest. She has led a national campaign demanding governments disclose their payment policies and the sums distributedi.

Wan says Chinese representatives talked about the payment policy before a UN group in September to show the country's progress in safeguarding children's rights.

"They boasted of making allowances available to more than 7,000 children with HIV/Aids, but what we've learned it is a different picture," Wan said.

Sun Ya, an Aids activist from Zhengzhou in Henan whose 17-year-old son contracted HIV from a blood transfusion in 2002, says his family has not received assistance under the Ministry of Civil Affairs policies.

Apart from the financial problems, Sun says children affected by HIV/Aids are haunted by a social stigma as they age and are likely to struggle with dating, having relationships and families.

Liu Yang, a fourth-year medical student in Zhengzhou, says his life was turned upside down after his mother was diagnosed with HIV in 2004.

His sister left school to work to help his father with saving money for his education. Liu was able to finish middle school and college because of additional financial assistance from the Hong Kong-based Chi Heng Foundation. He is still cautious, though, about telling friends about his family for fear of being shunned.

Liu says he frets about telling a future girlfriend about his mother, who takes medication to keep from developing Aids.

"I would lie if I said I don't worry, but I suppose I can't do much but to wait for someone who cares about me more than my family," he says.

This article appeared in the South China Morning Post print edition as Aids on mainland still a stigma